1. Field of the Invention
The invention relates to a method and arrangement for measuring and testing a vehicle frame, especially a truck frame or bus frame.
2. Description of Related Art
The prior art already discloses methods for measuring and testing a vehicle frame, on a rim of a vehicle wheel an axle measurement holder for a laser source and for a measurement scale being attached from the outside. From the outside, a reflector is attached to the frame and reflects a laser beam emitted by the laser source in the direction to the measurement scale on the axle measurement holder. If the reflector is attached to different locations of the frame and a laser beam measurement is taken at each location, the deformation of the frame can be deduced from the deviation of the laser incidence points on the measurement scale. There is a corresponding laser source with a measurement channel and a reflector on each longitudinal side for measuring the vehicle frame.
It is disadvantageous in the known methods for measuring and testing of vehicle frames that possibly add-on parts on the frame must be removed in order to attach the reflector to the frame; this is labor-intensive and time-consuming. Otherwise, the reflector which projects laterally far above the frame in the longitudinal direction of the frame cannot be attached at just any point on the frame. Since the laser source projects over the vehicle wheel rim to the outside, the reflector must also extend accordingly far to the outside; this can lead to measurement errors in the frame measurement for certain deformations of the frame. This applies especially when on the two longitudinal sides of the vehicle there are corresponding measurement devices to measure the frame completely, i.e., on two longitudinal sides. Measurement errors can occur especially when the frame is bent around a vertical axis (major axis) of the vehicle and/or around the longitudinal axis.
A measurement system for wheel angles and for positions of the chassis units of a motor vehicle is disclosed by German Patent DE 695 22 937 T2 and corresponding to U.S. Pat. No. 5,852,241.